1. Field of the Invention
This invention relates generally to a motor vehicle driveline and, more particularly to an all-wheel-drive (AWD) powertrain that transmits power continually to the wheels of a primary axle and selectively to the wheels of a secondary axle.
2. Description of the Prior Art
Driveline oscillations can occur when a vehicle equipped with front wheel drive (FWD) based AWD accelerates on a surface having a low coefficient of friction, such as a surface covered with ice or snow. During an aggressive acceleration on the surface, front and rear tires begin to slip at different times causing energy stored in the driveline to be released and the vehicle driveline to oscillate torsionally. The driveline oscillations can cause premature failure of driveline components and noise and vibration inside the vehicle.
These oscillations occur when the rear wheel speeds over-run the front wheel speeds in an active clutch based AWD system.
Unsatisfactory solutions include merely reducing the noise through increased use of sound deadening materials and truncating the peak torque commanded by the AWD system.
A need exists in the industry for a technique that detects the speed over-run, releases the energy stored in the driveline and reduces the torque in the AWD system.